1. Field of the Invention
The present invention relates to substrates provided with a photocatalytic coating, and to the process for producing such a coating and to its various applications.
It relates more particularly to coatings comprising semi-conducting materials based on metal oxide, in particular on titanium oxide, which are capable of initiating radical reactions under the effect of radiation of appropriate wavelength, resulting in the oxidation of organic products. These coatings thus make it possible to confer novel functionalities on the materials, which they cover, in particular dirt-repellent, fungicidal, bactericidal, algicidal or odour-controlling properties, optionally in combination with hydrophilic or anti-condensation properties, and the like.
2. Discussion of the Background
Highly diverse substrates have to date been envisaged, in particular construction materials used in the field of construction or vehicles (windows, facing, cladding or roofing materials, and the like) or materials used in purification processes.
International Patent Applications WO97/10186 and WO97/10185 have thus made known coatings comprising anatase, crystallized TiO2 with photocatalytic properties, coatings obtained from the thermal decomposition of appropriate organometallic precursors and/or from “precrystallized” TiO2 particles, suited in particular to deposition as a thin layer on glass in order to preserve its optical quality.
Patent Application EP-A-0,306,301 has also made known the use of photocatalytic TiO2 on fibrous materials used to purify the air, the deposition of the TiO2 being carried out by a process of sol-gel type.